In-line roller skating has become a very popular activity and is practiced as an exercise and a sport, but also as a means for sightseeing or for commuting in general. In-line roller skates are therefore increasingly used on roads and on generally rough or hard surfaces which are often very uncomfortable for the skater as the bumps, cracks and holes of any shape and size induce shocks and vibrations of the wheels which are transferred directly to the foot of the skater. The skater's feet may become numb from repeated vibrations induced by rough surfaces and joints, including the ankle joints and the knee joints, and muscles may become sore from repeated shocks.
To alleviate this problem, in-line skates may include a suspension system of some sort disposed between the chassis carrying the wheels and the skate boot in order to separate the two components and therefore reduce the transfer of shocks and vibrations from the wheels to the skate boot. For example, a particular in-line roller skate sold under the trade-mark Bauer® comprises a thin, flat elastomer component fitted between the chassis and the skate boot. The elastomer component is rigidly sandwiched between the chassis and the skate boot and provides some dampening of shocks and vibrations transferred from the wheels to the skate boot.
Other suspension systems have been devised which aim at absorbing vibration and shocks by pivotally connecting the chassis to the skate boot. One such design is disclosed in U.S. Pat. No. 5,842,706 to Sreter in which the skate boot is pivotally mounted to the chassis at the front end thereof and is connected at the rear portion of the chassis via a spring, guiding post and mounting socket assembly which allows the skate boot to move vertically relative to the chassis thereby absorbing some of the shocks and vibrations induced by a rough surface at the heel portion of the boot. However, since the front portion of the chassis is secured to the skate boot through a pivot pin, shocks and vibrations are transferred to the boot unhindered or undampened.
Another more-elaborate suspension system is disclosed in International application No. PCT/US97/00387. The system consists of a front and rear double pivot mechanism disposed between the skate boot and the chassis. The double pivot mechanism includes a first pivot mounted to the skate boot, a pivot member rotatably connected to the first pivot and having a second pivot attached to the chassis. A resilient member is disposed between the skate boot and the pivot members of each double pivot mechanism such that the front and rear portions of the skate boot are partially isolated from the chassis and shocks and vibrations are partially transferred through the mechanical pivots yet partially absorbed by the resilient members.
These suspension or vibration absorption systems represent a compromise between the required firmness and responsiveness of an in-line skate and a minimum degree of comfort for the legs of the user. Indeed when a chassis is allowed to move relative to the skate boot or when a soft material is positioned between a chassis and the skate boot, the chassis is able to sway laterally as well as vertically and the responsiveness of the skate is greatly diminished. A chassis mounted to a skate boot in the manner described above has an inherent tendency to become misaligned vertically and laterally relative to the skate boot during various maneuvers where high forces are applied to the in-line skate such as when turning or accelerating. The chassis is somewhat loosely connected to the skate boot because of the flexibility of the mechanical fittings of the various moving parts or of the soft material positioned between the chassis and the skate boot.
Hence prior existing suspension and/or vibration absorption systems for in-line skates are less responsive and somewhat unstable at high speed as well as in turning maneuvers than a skate with a rigidly mounted chassis.
Thus there is a need for an in-line roller skate having a suspension/vibration absorption system which is able to reduce the transfer of shocks and vibrations to the foot of the skater yet remains responsive and firm during various maneuvering.